Stereotype mat



Patented T OFFICE ii'EERlEOTYPE MAT 'Arlie W. Schorger, Madison, Wis,assignor to Burgess illellulose Company, Freeport, 11L, a. cor

poratiorl oi lllelaware Hamming. Application October 17, race. SerialNo. 361,606

11 Claims.

This invention relates to stereotype mats, particularly those known. asdry mats, and is directed to the improvement of such mats whereby theirmolding and casting properties are improved. 'Ihe invention relates tothe improved stereotype mat and to'the method of making the same.

It is the object or the invention to provide a stereotype mat havingimproved plasticity during molding whereby it is adapted to receive adeep, sharp, and clear-cut impression from the mold with a minimum offracture in the face.

It is also an'object of the invention to provide an improved stereotypemat which will give a largenumber of casts which are excellentreproductions of the pattern.

The stereotype ma}; which is incommon use is a relatively thick,moisture-absorbent fibrous: sheet which is composed of cellulose fibers,such as rag stock, cotton linters and chemical woodpulp, usually sulfltepulp. It usually contains a invention to provide a stereotype mat inwhich these properties are modified to advantage.

In accordance with the present invention, it

has been discovered that ifcertain proteins, in

formed into a sheet of the desired thickness. .The

sheet is then dried and calendered to produce the desiredsmooth-surfaced stereotype mat. A filler such as is usually used in thestereotype mat art, for example, clay, talc, etc., may be mixed with thefibers and protein and thus incorporated 1 in the resulting mat.

filler, such as clay, talc; etc., mixed with the fibers. Examples ofsuch stereotype. mats are disclosed in my United States Patents1,524,155, granted January 27, 1925, and 1,720,243, granted July 9,1929. The surface of the mat which is to receive the impression of themold may be given. a coating to improve its uniformity and smoothness.An example of'such a coating treatment is disclosed in my Patent1,863,731, granted June 21, 1932.

The matis moistened for the operation of receiving the impression fromthe pattern, and in this condition must be capable of readily undergoingcompression and stretch in order to form an exact reproduction of thepattern which often contains fine details. After the molding operation,the mat is dried,-and in this condition it must be hard and have auniformly smooth surface in order that a large number of accuratereproductions may be made by casting molten stereotype metal against it.If fractures are present, the molten metal flows into them, entiremovalof the solidified metal causes tearing oi. the surface of the mat. Thepresent invention results in improved plasticity for the moldingoperation, and improved smoothness and freedom from fracture for thecasting operation.

Plasticity of the mat in its moistened condition is of utmost importancein order thatthe mat may take, readily, and without the application ofexcessive pressure, a full and exact intpressionoi the pattern or form;Cellulose fibers themselves, possess only limited plasticity, theimpression taken by the mat being due largely to the compression andstretch which the fibers undergo. A sheet of cellulose fibers hascharacteristic limitations with respect to compression and stretch, andit is the purpose of the present Suitable proteins are the vegetableproteins andcasein. Casein is derived from milk and is commonlyconsidered to be an animal protein. In reality it is closely related tovegetable proteins and is not so far removed from the vegetable proteinfrom which it is derived that it has lost the essential characteristicsof vegetable protein.

Many vegetable products which are high in protein may be used. While theprotein may be isolated from the natural vegetable product for use inthe invention, it is satisfactory, and usually more economical, to usethe protein-bearing vegetable products in their natural state, andmerely comminute them to the desired particle size. Some of thecommercially obtainable protein-bearing vegetable products which may beused are given inthe following list, the approximate content of proteintherein being given 0pposite each item. The percentages are of proteinin the crude form, since it does not need to be refined for the purposesof this invention.

Conn protein product marketed under the trade mark li/Iazein" Soybeanmeal 3M8 Some of the vegetable products, such'as cottonseed meal andlinseed meal, contain a rela-.- tively large proportion of oils andfats. In such case, it is preferable that most of the oil and fat beremoved by expression or extraction before the material is incorporatedin the mat.

The quantity of protein which may be incorported in the stereotype matmay vary over a considerable range. As little as 5% of protein, basedupon the dry weight of the stereotype mat, produces a pronounced effectin increasing the plasticity. The effect is augmented with increasingprotein content, and a 50% protein content provides plasticity of a veryhigh order. This is themaximum protein content which it is vdesirable toemploy. The preferred range is from to 30% of protein. Where a naturalprotein-bearing material is employed, and the mat contains a filler, themat is composed of cellulose, filler, protein and the non-proteinconstituents of the protein-bearing material. The cellulose fibersimpart firmness and strength to the mat, and it is desirable that thecellulose content of the stereotype mat be at least 20% of the totalsolids. As an example of the present invention, a stereotype mat is madeof a mixture which is 60% by weight of cellulose fibers and 40% byweight of soybean flour. Such a stereotype mat contains approximately16% of crude protein.

The molding operation is carried out at room temperature or at anelevated temperature, depending upon the practice of the particularuser. The increase of plasticity is realized in either case. The air-drymoisture content of the stereotype mat is from 5% to 8%, and prior tothe molding operation, it is moistened until it has a water content ofapproximately 10% to 50%, based upon the weight of the mat. In thiscondition, it is pressed against the form which carries the printing orother characters or design which it is desired to reproduce. This formmay be either hot or cold, as explained heretofore. In either case, themat containing protein possesses greater plasticity to a pronounceddegree in comparison with a similar mat which does not contain protein.The plasticity is somewhat higher if a hot form is used. As a result, adeep mold is obtained with moderate pressure, and fine details arereproduced with great accurateness. After the molding operation, thestereotype mat is dried by means of suitable drying apparatus. For thisoperation, it may be removed from the form, or the form, withoutdisturbing the mat, may be transferred to the drying apparatus. Afterthe matis dry, it has a uniformly smooth hard surface, free offreetures, and many casts can be made from it.

The mat of this invention provides the additional advantage that itpossesses greatly increased plasticity even when the moisture content islow. A moisture content of from 10% to is sufficient to realize theadvantage of high plasticity. The time and cost of drying is reduced asa result. Savings in time are of essential importance where the mat isbeing used in a newspaper plant.

Suitable antiseptlcs for preventing or retarding the growth of molds andbacteria are incorporated in the mat.

In the foregoing description, the protein is in a finely divided solidcondition when it is incorporated with the cellulose fibers. It may beincorporated in the dissolved condition, also. For this purpose, theprotein is brought into solution in a suitable aqueous alkalinesolution, for example, a solution of a carbonate or hydroxide of analkali metal. This solution is then mixed with the cellulose fibers, andthe mass is treated with an acid to neutralize the alkali andprecipitate the protein insitu. For convenience and simplicity and alsofor the most satisfactory results, it is preferred that the protein bein the finely ground solid state. The particles shopld be sumcientlyfine that substantially all pass through a 100 mesh per inch sieve(particle diameter 0.0059 inch), and preferably through a 200 mesh perinch sieve (particle diameter 0.0029 inch).

The protein may be treated with an aldehyde, such as formaldehyde, orwith an tannin, and the plasticity obtained by the use of such treatedprotein in the stereotype mat is substantially the same as that obtainedwhen protein itself is used.

The following are several specific examples of methods for carrying outthe present invention. It is understood that the invention is notlimited to these specific methods, but only in accordance with the scopeof the appended claims.

' Example No. 1

A water suspension is made containing 60 parts by weight of cellulosefibers, 40 parts of soybean flour which has been ground to a size whichwill pass through a 200 mesh per inch sieve, and 50 parts of clay. Thewhole is mixed uniformly and then the solids are felted into a sheet ofthe desired thickness on a paper machine in a manner well known to thoseskilled in the art, and the sheet is dried and calendered. The thicknessof the finished sheet may vary from 0.015" to 0.036", as desired. Thedried and calendered sheet is then humidified until it has taken upmoisture suflicient to produce a water content of from 10% to 50%,depending upon the moisture requirements for the particular application.After the moisture becomes distributed uniformly, the sheet is ready forthe molding operation, Y

Example No. 2 v

A water suspension containing 80 parts of cellulose fibers, 50 parts ofclay, and 20 parts of casein, ground to pass through a 200 mesh per inchsieve, is mixed thoroughly. A mat is formed from this suspension in amanner similar to that described in Example 1.

Satisfactory results are obtained employing similar quantities ofMazein" in place of casein in the procedure of this example.

Example No. 3

A water suspension is made or an intimate mix- .ture of parts ofcellulose fibers, 40 parts of cottonseed flour (approximately 15 partsof crude protein) and 5 parts of talc. forming the stereotyp mat fromthe suspension is the same as in Example 1.

Example No. 4

A water suspension is made composed of a mixture of 100 parts ofcellulose fibers, 40 parts of linseed flour (approximately 15 parts ofcrude protein) and 50 parts of talc, the subsequent procedure beingsimilar to that of Example 1.

Excellent results are obtained if 40 parts of pea flour (approximately10 parts of crude protein) is employed in the procedure of this examplin place of the linseed flour.

The term protein as employed in the claims is intended to cover thenatural protein-bearing vegetable substance as well as the isolatedprotein. and where proportions are given, they repre- The procedure of 1sent proportions of the isolated protein. While it is stated throughoutthe specification that the protein is in crude form. the invention isnot limited to such protein, and refined protein may be used as well.

I claim:

1. A fibrous stereotype mat having incorporated among and in intimatemixture with the fibers thereof, at least approximately 5%, based .onthe-weight of said stereotype mat, of finely "divided particles ofprotein from th group consisting of vegetable protein and casein, saidprotein and fibers comprising, respectively, at least approximately 5%and 20% of the weight of said mat.

3. A fibrous stereotype mat having inco porated among and in intimatemixture with the fibers thereof, at least approximately 5%, based on theweight of said stereotype mat, of finely divided particles of proteinIrom the group consisting of vegetable protein and casein, substantiallyall of said particles being of a size adapted to pass. through a 100mesh per inch sieve.

4. A fibrous stereotype mat having incorporated among and in intimatemixture with the fibers thereof, at least approximately 5%, based on theweight of said stereotype mat, of finely divided particles of proteinfrom the group consisting of vegetable protein and casein, substantiallyall of said particles being of a size adapted to pass through a 200 meshper inch sieve.

5. YA fibrous stereotype mat having incorporated among and in intimatemixture with the fibers thereof from approximately 5% to approximately50%, based on the weight of said si reotype mat, of finely dividedparticles of protein from the group consisting of vegetable protein andcasein.

6. A fibrous stereotype mat moistened with water and having incorporatedamong and in intimate mixture withthe fibers thereof, at least 5% basedon th dry weight of said stereotype mat, of finely divided particles ofprotein from the group consisting of vegetable protein and casein.

'7. A fibrous stereotype mat having a water content of from 10% to 50%of the total weight thereof, and having incorporated among and inintimate mixture with the fibers thereof, at least approximately 5%,based on the dry weight of said stereotype mat, of finely dividedparticles of pr'tein from the group consisting of vegetable protein andcasein.

8. A sheet-form fibrous stereotype mat having a thickness ofapproximately 0.015" to 0.036", said mat being composed of cellulosefibers and having incorporated among and in intimate mixture with thefibers thereof, at least approximately 5%, based on the weight of saidstereotype mat, of finely divided particles of protein from the groupconsisting of vegetable protein and casein.

9. A fibrous stereotype mat having soy. bean flour distributed among andin intimate mixture with the fibers thereof, the protein 01' said soybean flour comprising at least approximately 5% and the fibers at leastapproximately 20%, of the weight of said stereotype mat.

10. A fibrous stereotype mat having incorporated among and in intimatemixture with the fibers thereof, at least approximately 5%, based on theweight 01 said stereotype mat, of finely divided particles of vegetableprotein.

11. A fibrous stereotype mat having incorporated among and in intimatemixture with the fibers thereof, at least 5% based on the weight of saidstereotype mat, of finely divided particles of casein. g

ARLIE W. SCHORGER.

